ISB 399 

R3 
Jopy 1 



Issued March 22, 1913. 

J. S. D.EPARTMENT OF AGRICULTURE. 

BUREAU OF PLANT INDUSTRY— BULLETIN NO. 276. 

B. T. GALl.UWAV. Chief of Bureau. 



THE UTILIZATION OF WASTE KAISIN SEEDS. 



FRA\'K RABAK, 

Chemual Biologist, iJrng-Plunt, Poisonous- Plant, riiysiologicul, 
and FiTmentation Investigations. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1913. 



Honngnf^t 






Issued March 22, 1913. 

U. S. DEPARTMENT OF AGRICULTURE. 

BUREAU OF PLANT INDUSTRY— BULLETIN NO. 276. 

B. T. GALLOWAY, Chief of Bureau. 



THE UTILIZATION OF WASTE RAISIN SEEDS. 



FRANK RABAK, 

Chemical Biologist, Drug-Plant, Poisonous-Plant, Physiological, 
and Fermentation Investigations. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1913. 



u 




-^7 



0?^ 



BUREAU OF PLANT INDUSTRY. 



Chief of Bureau, Beverly T. Galloway. 
Assistant Chief of Bureau, William A. Taylor. 
Editor, J. E. Rockwell. 
Chief Cleric, James E. Jones. 



Drug-Plaxt, Poisonous-Plant, Physiological, and Fermentation Investigations. 

SCIENTIFIC staff. 

Rodney H. True, Physiologist in Charge. 

A. B. Clawson, Heinrich HasseUjring, C. Dwight Marsh, W. W. Stockberger, and Walter Van Fleet, 

Physiologists. 
Carl L. Alsberg, H. H. Bartlett, Otis F. Black, H. H. Bunzel, Frank Rabak, and A. F. Sievers, Chemical 

Biologists. 
W. \V. Eggleston, Assistant Botanist. 

S. C. Hood, G. F. Mitchell, James Thompson, and T. B. Young, Scientific Assistants. 
Hadleigh Marsh, Assistant. 
G. A. Russell, Special Agent, 
276 



D. ar D. 

APR 2 1913 



ADDITIONAL COPIES o f this publication 
-t\. may be procured from the Superintend- 
ent OF Documents, Government Printing 
Office, Washington , D. C. , at 5 cents per copy 



LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 

Bureau of Plant Industry, 

Office of the Chief, 
WasMngton, D. C, November 18, 1912. 
Sm: I have the honor to transmit herewith and to recommend for 
pubUcation as Bulletin No. 276 of the series of this Bureau the accom. 
panying manuscript entitled "The Utilization of Waste Raisin Seeds," 
by Mr. Frank Rabak, Chemical Biologist, submitted by Dr. R. H. 
True, Physiologist in Charge of the Office of Drug-Plant, Poisonous- 
Plant, Physiological, and Fermentation Investigations. 

This investigation deals with the utilization of a by-product of an 
agricultural industry which has hitherto been disregarded. It has 
been shown that the seeds removed from raisins yield technically 
useful products, which by their value fully justify the expense 
involved in separating them. It is believed that this situation is 
typical of many so-called agricultural waste products which are at 
present not fully utilized. 
Respectfully, 

B. T. Galloway, 

Cliief of Bureau. 
Hon. James Wilson, 

Secretary of Agriculture. 

27(5 3 



CONTENTS, 



Page. 

Introduction 7 

Accumulation and present disposal of raisin seeds 7 

Examination of raisin seeds for commercial products 10 

Sirup 12 

Preparation 12 

Physical properties 12 

Chemical examination 12 

Sugars 12 

Acids 13 

Production of alcohol 13 

Commercial uses 13 

Available quantity and value 14 

Fixed oil 14 

Extraction and physical properties 14 

Chemical examination 14 

Free acids 14 

Saponification value 15 

Todin absorption 15 

Volatile acids 15 

Soluble acids 16 

Insoluble acids 16 

Acetyl value 16 

Unsaponifiable matter 17 

Detailed examination of the insoluble acids 17 

Mixed acids 18 

Separation of the solid antl liquid acids 18 

Solid acids 19 

Liquid acida 21 

Drying property of raisin-seed oil 23 

Comparison of raisin-seed oil with other drying oils 25 

Raisin-seed oil as a paint and varnish oil 28 

Raisin-seed oil as a soap-making oil 29 

Available quantity and value 30 

Tannin 30 

Extraction 30 

Analysis 30 

Dyestuff 31 

Use of the extract in tanning 32 

Available quantity and value 33 

Meal 33 

Value as stock food 33 

Available quantity and value 35 

Summary 35 

276 5 



LUSTRATIONS. 



Page. 
Flu . 1 . Waste raisin seeds 8 

2. Raisin seedinc mafhine in operation 10 

3 . Commerf 'ial j)roducts from waste raisin seeds 11 

276 
6 



B. P. I. 



THE UTILIZATION OF WASTE RAISIN SEEDS. 



INTRODUCTION. 

In the canning and packing operations of the fruit industry in the 
United States certain by-products ahnost invariably result, many of 
which, because of lack of utilization, become in the true sense waste 
products. In the commercial canning and drymg of peaches, apricots, 
and prunes the pits were formerly to a large extent waste material. 
Through an investigation recently made in the Bureau of Plant In- 
dustry,^ however, valuable uses were discovered for this material, and 
as a consequence it is now used in the manufacture of many imjjortant 
commercial products. In the raism-seeding industry, which within 
recent years has grown to such proportions in the grape-produchig 
sections of (California, vast quantities of seed accumulate annually 
(fig. 1 ) . Thus far this material has been practically wasted, and it was 
with the object in view of ])reparing ])roducts of commercial value from 
these waste raisin seeds that the investigation herein described was 
undertaken. 

ACCUMULATION AND PRESENT DISPOSAL OF RAISIN SEEDS. 

vSome idea may be gained of the vast accumulation of raisin seeds 
when it is considered that 30,000 to 40,000 tons of I'aisins are seeded 
annually. By actual test it has been found that 9.75 or approxi- 
mately 10 per cent of the fruit consists of seeds. There should there- 
fore be in the neighborhood of 3,000 to 4,000 tons of this material 
available each year. Within the past few years the matter of utilizing 
waste raisin seeds has been receiving some attention from the produc- 
ers, but thus far with little success. From the uiformation at hand 
it appears that a brandy has been made by fermenting the sugary 
matter which adheres to the seeds. A high-proof alcohol has also 
been distilled after the fermentation. It has been reported that some 
fixed oil has been obtained, but whether or not this has proved suc- 
cessful is not definitely known. 

In this connection it seems desirable to mention also the possible 
utilization of grape seeds, of which there is a large accumulation from 
the residues of wineries and grape-juice factories in this country. 

1 Rabak, F. Peach, apricot, and prune kernels as by-products of the fruit industry of the United States. 
Bulletin U3, Bureau of Plant Industry, U. S. Dept. of Agriculture. 190S. 

276 7 



8 UTILIZATION OF WASTE RAISIN SEEDS, 

The utilization of these seeds has received considerable attention in 
the past from foreign wine growers, but with only a limited degree of 
success. This may be due to the fact that only one constituent, 
namely, the fixed oil, seemed to be made use of. In 1827 Fontenele ^ 
stated that it had long been known tlmt grape seeds contam a fixed 
oil, but that in France there was lack of knowledge with regard to its 
extraction. For several 3^ears prior to this time the oil had been used 
in Italy to a certain extent for illummating purposes, rivaling olive 
oil from the standpoint of light, clear flame, and lack of odor. This 
was brought to the attention of agriculturists for the reason that the 




Fig. 1.— Waste raisin seeds. 

seeds were bemg lost to them. Accordmg to Fontenele 60 pounds of 
the seeds produced 6 pounds of oil. 

In 1828 Schiibler ^ stated that for a long time the seeds of grapes 
had been utilized in the southern regions of Europe for their oil, which 
was used as an edible oil. It was said that the oil possessed illumi- 
nating properties, burning slowly in common lamps, being similar in 
this respect to poppy-seed oil, tobacco-seed oil, and the slow-burnmg 
rapeseed oil. The following year it was reported that the oil had 
been produced in a small way in Wurttemberg, but with no great 

' Fontenele, J. Sur I'extraction de I'huile des p^pins de raisins. Journal de Chimie M^dleale, vol. 3, 
1827, p. 66. 

2 Schiibler, G. Untersuchungen iiber die fetten Oele Deutschlands in Beziehiing auf Hire wichtigeren 
physisehen Eigensehaften, 18. Oel der Weintraubenkerne, von Vitis vinifera L. Journal fur Technische 
und Okonomische Chemie, vol. 2, 1828, p. 364. 



/ 

/ 



ACCUMULATION AND PRESENT DISPOSAL OF RAISIN SEEDS. 9 

success/ In Wurttemberg alone at that time it was calculated that 
340,000 pounds of grape seeds were lost annually. 

According to Minutoli - the oil was said to be useful for soap-making 
purposes and when used in salad it was not without a pleasant taste. 

The method employed for extracting the fixed oil consisted in 
separatmg the husks and stems from the seeds by drying and passing 
■them through sieves.^ The dried seeds were ground to a meal, placed 
in a co])per kettle, and one-third or one-fourth their weight of water 
.added. Heat was applied and the mass was stirred continually to 
prevent the formation of lumps. When free fixed oil appeared upon 
pressure between the fingers, the mass was put into canvas bags and 
placed m an oil press. The cake was again treated in a similar manner 
and another quantity of oil produced. In this way from 10 to 20 per 
cent of oil was obtained from the seeds. 

Marre ^ has recently called attention to the need of reviving this 
industry and states that in France in the Departments of Gard, 
Herault, Aude, and the Pyrenees-Orientalos there are at least 28,000,- 
000 hundredweight of grapes, or about 1,030,000 hundredweight of 
seeds, from which, provided a yield of 15 per cent of oil were obtained, 
there would result 155,000 huntlredweight of oil, valued roughly at 
11,655,000 francs. 

According to Paris,'' wine residues consist of 25 to 30 per cent of 
stems, 50 to (iO per cent of skins, and 15 to 20 per cent of seeds, the 
total residue comprising about 15 to 25 ])er cent of the grapes. After 
extracting the oil the seeds contain 10. G per cent of moisture, 9.12 per 
cent of crude })rotein, 4.2 per cent of crude fat, 45.2 per cent of crude 
fiber, 3.15 per cent of ash, and 27.6 per cent of nitrogen-free extractive 
matter, of which 11.5 per cent are carbohydrates and 12.4 per cent 
pentosans. The digestibility of the protein amounts to 70 per cent, 
fat 75 per cent, nitrogen-free extractive matter 85 per cent, and crude 
fiber 50 per cent. It is stated that the ash consists of 14.3 per cent of 
phos])horus pentoxid and 22.3 per cent of potassium oxid. 

It has but recently been reported*^ that grape-seed oil is an impor- 
tant product of the wine regions of France and Italy, where it is used 
as an edible oil and in the manufacture of soap. It is stated that 3 
pounds of the oil will make 5 pounds of soap of good quality. The oil 
is extracted by hot or cold pressure or by solvents. On account of its 
high protein content the meal is said to be eaten by cattle with relish. 

1 Schiibler, G. Darstellung des fetten Oels aus dem Kemen der Weintrauben. Journal fiir Techuische 
und Okonomische Chemie, vol. 5, 1S29, p. 31. 

2 Minutoli. Bemerkung iiber die Anwendung der Traubenkerne zur Oelbereitung. Journal fiJr Tech- 
nische und Okonomische Chemie, vol. 10, 1831, p. 352. 

3 Gel aus Traubenskernen. Dinger's Polytechnisches Journal, vol. 14S, 1858, p. 238. 

* Marre, F. L'huile des pepias de raisin. Revue Gencrale de Chimie Pure et Appliquco, vol. 14, 1911, 
p. 186. 
5 Paris, G. I Vinaceioli. Le Stazioni Sperimentali Agrarie Italiane, vol. 44, 1911, fase. S-9, p. 669. 
Grape-seed oil. Pure Products, vol. 8, 1912, p. 217. 

71319°— Bul. 276—13 2 



10 



UTILIZATION OF WASTE RAISIN SEEDS. 



EXAMINATION OF RAISIN SEEDS FOR COMMERCIAL PRODUCTS. 

The successful and profitable utilization of raisin seeds will depend 
not only upon the preparation of the various products obtainable, but 
also upon the practical uses to which they can be put. The object 
of this paper is to show not only what products can be made from the 
seeds, but also to point out the various channels of trade into which 
ihej may go m order to serve as unportant practical commodities. 

The first step in the process of examination was to make use of the 
sugary matter which adheres to the seeds as they come from the 
seeding machines (fig. 2). From this material a very desirable sirup 




Fig. 2. — Raisin seeding machine in operation. 

was prepared (fig. 3). The next step was to determine the quantity 
of fixed oil, smce it is known that the seeds of practically all fruits 
contain fatty or fixed oil to a greater or less extent and that many 
such oils are important articles of commerce, entering mto the manu- 
facture of paints, varnishes, soaps, etc. (fig. 3). From the astringent 
taste of the seeds the presence of tannin was suspected, and smce 
tannins are valuable articles of commerce a determination of the 
tannin content was next made (fig. 3). As a final product, after 
the extraction of the fixed oil and the tannm, the residue was ana- 
lyzed for its possibilities as a stock food (fig. 3). 

In the following pages each of the products mentioned is discussed 
separately in regard to methods of preparation, extraction, chemical 

276 



EXAMINATION OF KAISIN SEEDS FOR COMMERCIAL PRODUCTS. H 

analysis, application in commerce, the approximate quantity availa- 
ble, and the probable value. The investigation of the seeds was 
taken up systematicaUy, in order that every available constituent 




m 



S50 /a 7-^o /or/s: \s/rup. ffeA/. 
96. cot '/o/^e.o. 'o c/a^S^/,oc/ii /p 






^r7nua/ dxy/pu/, 3.0OO 
/a -4,000 /'o/Ts. 




330 /o-^^S fons. 



/a/?m>7 &f//2f^/; /,<SOO A? 

e.^oo/orrs. 



Fig. 3.— Commercial products from waste raisin seeds. 

which is capable of being extracted practically might be given careful 
attention and that as many articles of commercial value as possible 
might be produced. 



12 UTILIZATION OF WASTE EAISIN SEEDS. 

SIRUP. 
PREPARATION. 

As the initial step in the process of utilizing the waste raisin seeds, 
the material, which consisted of a sticky mass of seeds and pulp, was 
washed with cold water to remove the adhering pulp. The solution 
thus obtained was distinctly sweet and it was thought it might be of 
value m the preparation of a sirup. It was therefore concentrated 
on a water bath, and a yield of 18.5 per cent of an agreeable sweet 
sirup was obtained, which possessed the characteristic raisin taste. 
As the material was received directly from the seedmg machines it 
represented, so far as the writer is aware, the average condition of 
raisin seeds with respect to the amount of adhering sugary matter, 
and these figures may therefore be taken as the average percentage 
of available sirup. It is probable, however, that seasonal conditions 
have a direct influence on the sugar content of the fruit and also that 
the effectiveness of the,machmes in removmg the pulp would affect 
the quantity of sirup obtainable, smce in some instances much more 
pulp is left adhering to the seeils than in others. 

PHYSICAL PROPERTIES. 

The sirup had a consistency about equal to that of strained honey 
and was reddish brown in color. The specific gravity at 22° C. was 
found to be 1.384. 

CHEMICAL EXAMINATION. 



The percentage of sugars })resent was determined by volumetric 
assay with Fehling's solution. One gram of the snup was found to 
reduce 122 cubic centmieters of Fehluig's solution. The dextrose 
factor for Fehluig's solution, previously ascertained, was 0.005. 
These results- show, therefore, that 1 gram of the sirup contams 0.61 
gram, or 61 per cent, of reducing sugars calculated as dextrose. 

A weighed portion of the sirup was subsequently inverted by the 
addition of a few drops of hydrochloric acid and heating on a water 
bath for one-half hour. By this operation the cane sugar and per- 
haps other polysaccharids were inverted to monosaccharids. The 
total reducmg sugars were then determined as glucose. The diifer- 
ence in the number of cubic centimeters of Felilmg's solution required 
before and after inversion corresponds to the cane sugar in the 
sample. Two grams of the sirup after inversion required 12.4 cubic 
centimeters of FehUng's solution m excess of the amount requii'ed for 
dextrose. From the cane-sugar factor of Fehling's solution (0.00475) 
the total amount of cane sugar in the 2 grams of sirup was 0.0589 
gram, which corresponds to 2.94 per cent of cane sugar. 

276 



SIRUP. 13 



In connection with the intensely sweet taste of the sirup a slightly- 
tart taste was noticeable, which was doubtless due to the presence 
of grape acids. The acidity was determined in terms of tartaric 
acid. Two grams of the sirup by titration with standard N/10 
potassium-hydroxid solution required 2.85 cubic . centimeters of 
alkali, which, from the tartaric-acid factor for decinormal alkali 
(0.007446), corresponds to 0.0212 gram of tartaric acid, or 1.06 per 
cent. 

This analysis of the sirup indicates the composition only in a very 
general way as far as sugars and free acidity are concerned. Many 
factors may enter to vary the composition. The consistency of the 
sirup will have much to do with the percentage of sugars; the more 
the sii'up is evaporated the liigher will be the percentage of sugar, 
and vice versa. 

PRODUCTION OF ALCOHOL. 

As the sirup contains such a large quantity of fermentable sugar, 
the commercial })r()duction of alcohol from this by-product should 
be feasible. In order to determine the amount of alcohol capable of 
being fermented, 150 grams of the sirup were dissolved m about a 
quart of water, to which a teaspoonful of fresh yeast was added. 
The mixture was allowed to ferment for about 24 hours at a tempera- 
ture of 30° C, or until the evolution of carbon dixoid ceased. After 
filtering the solution it was acidified with phosphoric acid to neutral- 
ize any volatile alkahs which may have been present. The solution 
was distilled over a direct flame until all of the alcohol was removed 
from the flask. After making alkahne with potassium-hydroxid so- 
lution to neutrahze any volatile acids present and distillmg, 90 cubic 
centimeters of alcohol were obtained. The specific gravity of the 
alcohol was 0.930 at 22° C, which corresponds to 42 per cent of abso- 
lute alcohol by weight. The total amount of dilute alcohol therefore 
contained 35.1 grams of absolute alcohol. C^alculating from the 
amount of sirup used in the experiment, a total of 23.4 per cent of 
absolute alcohol can be obtained by fermentation of the sirup. 

From these results it is estimated that the total amount of alcohol 
(calculated as absolute alcohol) capable of being manufactured from 
the su'up would approximate 130 to 170 tons. This quantity of abso- 
lute alcohol would represent about 140 to 184 tons of alcohol U. S. P. 
(190 proof), which corresponds to 41,176 to 54 117 gallons. 

COMMERCIAL USES. 

With its agreeable flavor and sweet fruity taste, the sirup from 
raism seeds possesses qu ah ties which should make it useful in the 
household and also in various commercial industries. For instance, in 

276 



14 UTILIZATION OF WASTE EAISIN SEEDS. 

the making of mincemeat, in which large quantities of raisins are ordi- 
narily used, the sirup could be used to a certain extent at perhaps less 
expense, certainly with less labor, and still the peculiar and agreeable 
flavor of the raisins could be retained. For table use it would seem 
to be distinctly desirable , since the flavor and wholesomeness of the 
raisins are to a great extent retamed. A promment manufacturer of 
sirups for soda-f ountam use has pronounced it to be a most excellent 
flavor for carbonated diinks, and it should find use in this direction. 
The outlook, therefore, for creatmg a demand for this by-product 
is very promising. 

AVAILABLE QUANTITY AND VALUE. 

In view of its possible commercial uses, the question of the approxi- 
mate quantity available and the value of the sirup is unportant. 
Since 3,000 to 4,000 tons of seeds are available annually from the 
seeded-raisin. industry and since approximately 18.5 per cent of sirup 
is obtainable from this material, it follows that 555 to 740 tons could 
be manufactured yearly. This is the equivalent of 1,110,000 to 
1,480,000 pounds, or, calculatmg from the specific gravity of the 
sirup, 96,522 to 128,696 gallons. 

The value will, of course, depend largely upon the channels of trade 
into which it is directed. A conservative estimate, however, would 
place it at from $30,000 to $50,000 annually, provided a demand for 
the product is created in which its usefuhiess is assured, and it is not 
unreasonable to assume that some of the suggested uses will eventu- 
ally build up a steady demand for this product. 

FIXED OIL. 

EXTRACTION AND PHYSICAL PROPERTIES. 

After removing the sugary pul}), the seeds were screened, dried, 
and ground, and then extracted with ether in a continuous-extraction 
apparatus. A yield of about 14.5 per cent of a pale, golden-yellow 
oil was obtamed, which possessed a slightly fatty odor with a bland, 
nuthke taste. The specific gravity at 24° C. was 0.9220 and the 
mdex of refraction at 25° C. was 1.4702. 

CHEMICAL EXAMINATION. 

FREE ACIDS. 

The amount of free acids in the oil was ascertained by titrating 
a weighed quantity of the oil with alcoholic potassium hydroxid. 
One gram of the oil was found to require 1.25 milligrams of potassium 
hydroxid for neutralization, corresponding to 0.62 per cent of free 
acid calculated as oleic acid. 

276 



FIXED OIL. 15 



SAPONIWCATION VALUE. 



As a measure of the glycerids of fatty acids, the saponification 
number (Koettstorfer number) was determhied by heating a weighed 
quantity of the fixed oil with a definite volume of alcoholic potassium 
hydroxid and titrating back the excess of alkali with standard hydro- 
cliloric-acid solution. The saponification value, or the number of 
milligrams of potassium hydroxid required to saponify the fatty-acid 
glycerids in 1 gi-am of the oil, was found to be 188. 

lODIN ABSORPTION. 

Tlie property of iodin absorption possessed by fixed oils is dependent 
upon the presence of unsaturated fatty acids or fatty-acid glycerids. 
It is a property of all unsaturated fatty acids to take up iodin by 
direct addition, the amount absorbed depending upon the nature of 
the unsaturated compounds or the number of double bonds they 
contain. Saturated fatty acids and their glycerids containing no 
double bonds do not possess this property. Tlie iodin number is 
therefore an indication of the composition of a fixed oil as regards 
the content of unsaturated fatty acids and often determines the class 
of oils to which it belongs. 

Tlie iodin absorption of raisin-seed oil was determined in the 
usual maimer, that is, by allowing iodm to react under the conditions 
directed ^ with a definite quality of oil and titrating the excess by 
means of standard sodium-thiosulphate solution. The iodin absorp- 
tion (or Hiibl's) number was found to be 131. 

VOLATILE ACIDS. 

It has been stated that fixed oils consist largely of glycerids of 
fatty acids. The fatty acids in combination with glycerin may be 
either volatile or nonvohitile, the latter usually predominating. 
Fixed oils often contain in combination small quantities of some 
of the soluble volatile acids, such as butyric, valerianic, caproic, 
and caprylic, which decrease in solubility as well as in volatility in 
the order mentioned. The Reichert-Meissl number is a measure 
of the amount of volatUe acids present in a fixed oil and is indicated 
by the number of cubic centimeters of decinormal alkali required to 
neutralize the volatile fatty acids obtained from 5 grams of fixed oil. 

The determination of volatile acids was carried out in accordance 
with the method recommended by the Association of Official Agri- 
cultural Chemists ^ and consisted essentially in saponifying a weighed 
portion of the oil m 95 per cent alcohol by means of sodium-hydroxid 
solution, then evaporating the alcohol, dissolving the soap in water, 

1 United States Pharmacopoeia, 8th revision, p. 527. 

2 Official and provisional methods of analysis. Bulletin 107 (revised), Bureau of Chemistry, U. S. 
Dept. of Agriculture, 1910, p. 139. 

276 



16 UTILIZATION OF WASTE EAISIN SEEDS. 

acidifying, and distilling with steam. By titrating the distUlate 
with standard alkali solution the volatile-acid equivalent of 5 grams 
of fixed oil, expressed in cubic centimeters of tenth-normal alkali 
solution, was readily ascertained. By this method the Reichert- 
Meissl number, or the amount of volatile acids in the oil, was found to 
be 0.64, which indicates that a very small percentage of the lower 
volatile acids is present. 

SOLUBLE ACIDS. 

The percentage of soluble acids was also determined according to 
the method prescribed by the Association of Official Agricultural 
Chemists ^ and consisted in liberating the fatty acids from a saponified 
weighed portion of oil by the addition of a definite amount of half- 
normal hydrochloric acid. After washing the liberated fatty acids 
several times with hot water, the aqueous solution was titrated 
with tenth-normal alkali. By means of the factor 0.0088 the weight 
of the soluble acids in the saponified oil was calculated as butyric 
acid. By this method it was found that 6.697 grams of raisin-seed 
oil contained 0.0264 gram of butyric acid, which corresponds to 0.394 
per cent of soluble acids. 

INSOLUBLE ACIDS. 

The amount of insoluble fatty acids (Hehner value) was also deter- 
mined by the method adopted by the Association of Official Agricul- 
tural Chemists.^ The insoluble fatty acids remaining from the deter- 
mination of the soluble acids were dramed and dried. They were then 
transferred to a weighed dish and the filter paper through which the 
soluble acids had been filtered was washed with absolute alcohol and 
the flask which contained the insoluble acids was rinsed with absolute 
alcohol. The filtrate and washings were then added to the insoluble 
acids in the weighed dish. After drying in a desiccator, when the 
alcohol had evaporated and the weight of the acids had become con- 
stant, the weight of the insoluble fatty acids in the oil corresponded 
to a total of 94.4 per cent. Since the uses of an oil are largely de- 
pendent upon the nature of the insoluble acids which it contains in 
the form of glycerids and since so large a proportion of raisin-seed 
oil consists of insoluble acids, this subject will be discussed in detail 
later in this bulletin. 

ACETYL VALUE. 

As a measure of the hydroxylated glycerids in a fixed oil, the deter- 
mination of the acetyl value is usually made. Acetic-acid anhydrid 
is employed to react with the hydroxy groups that may be contained 
in the fatty acids, the acetyl radical (C2H3O) replacing the hydro- 
gen of the hydroxy (OH) group. The method used was again that 

1 Op. cit.,p. 138. 2 Op. cit., p. 139. 

276 



FIXED OIL. 17 

recommended by the Association of Official Agricultural Chemists.^ 
After acetylization of the oil with acetic-acid anhydrid it was washed 
free from excess acid and dried. By saponifying a weighed portion 
of the acetylated oil, dissolving the soap in water, and decomposing 
the soap with a quantity of sulphuric acid equivalent to the amount 
of potash added, the free acids were liberated. The insoluble fatty 
acids separated in the form of a layer, while the soluble acid (acetic) 
which was taken up during acetylization remained in solution. After 
carefully washing the oily acids with boihng water, the aqueous acid 
solution was titrated with standard alkali and the amount of acetic 
acid determined. 

The acetyl value of raisin-seed oil, after correcting for the soluble 
volatile acids as suggested by Lewkowitsch,^ was found to be 16, 
which indicates that 16 milhgrams of potassium hydroxid were re- 
quired to neutrahze the acetic acid obtained by the saponification of 
1 gram of acetylated oil. This value is consideralfh^ lower than the 
results obtained for grape-seed oil recorded by Marre,^ which varied 
from 20.8 to 25.0. 

UNSAPONIFIABLE MATTER. 

Besides the glycerids of fatty acids, most fixed oils contain small 
quantities of unsaponifiable matter, which consists principally of an 
alcohoHc substance, phytosterol, together with some coloring matter 
and compounds of a waxhke character. The amount of unsaponifi- 
able matter sometimes varies in the different oils, depending upon 
the condition of the material as well as the methods of extraction. 
Although these constituents are of little practical value, a determina- 
tion was made by saponifying a quantity of the oil with alcohohc 
potassium hj^droxid and subsequently shaking out the aqueous solu- 
tion of the soap with ether, and the oil was found to contain 0.78 per 
cent. The determination is useful chiefly for the detection of adulter- 
ations of vegetable oils with waxes, paraffin, or mineral oils. 

DETAILED EXAMINATION OF THE INSOLUBLE ACIDS. 

The insoluble acids, which comprise such a large proportion (94.4 
per cent) of the constituents of raisin-seed oil, determine in a general 
way the usefulness of this oil. Insoluble acids are variable in char- 
acter, some being sohd at ordinary temperatures and others hquid. 
Oils with solid acids predominating are usually found useful in the 
manufacture of soaps, as, ft)r instance, coconut and palm oils, which 
contain large quantities of such solid acids as stearic, palmitic, and 
myristic. 

1 Op. cit., p. 142. 

2 Lewkowitsch, J. Chemical Technology and Analysis of Oils, Fats, and Waxes, vol. 1, 1909, p. 342. 

3 Marre, F. L'huile des p^pins de raisin. Revue G^n6rale de Chimie Pure et Appliqu^e, vol. 14, 1911, 
p. 186. 

71319°— Bul. 276—13 3 



18 UTILIZATION" OF WASTE IIAISIN SEEDS. 

The nature of the hqiiid acids of an oil also determines in many 
cases its practical application. Certain liquid acids are useful in soap 
making, while others possess dr^ang properties, depending largely 
upon their constitution. It must be understood, however, that the 
free acids are not found to any great extent in a fixed oil, but are 
present as glycerids. 

The insoluble acids of raisin-seed oil are both soHd and hquid. 
Since the liquid acids are greath- in excess, the mixed acids when 
liberated from the oil are liquid. 

Mixed Acids. 

The insoluble acids separated from the oil after saponification by 
the addition of h3^drochloric acid were obtained in the form of a 
golden-yellow hquid with practically no odor and with a bland, fatty 
taste becoming slightly bitter. The specific gravity at 24° C. was 
0.8948, and the index of refraction at the same temperature was 
1.4622. The acids began to congeal at 12.5° C. and were entirely 
sohdat 11.5° C. 

By titrating the oil with standard potassium hydroxid the neutral- 
ization value of the mixed acids was found to be 174.5. The iodin 
value, determiined in the manner previously mentioned, was 137. 

Separation of the Solid and Liquid Acids. 

In order to separate the solid and hquid acids in the mixture, the 
lead-ether method was used. The effectiveness of this method depends 
upon the insolubihty of the lead salts of the sohd fatty acids in cold 
ether, the lead salts of the hquid acids being soluble. The method 
used for the preparation of the lead salts of fatty acids was that 
recommended by the Association of Official Agricultural Chemists 
under the test for peanut oil.' After saponifying about 5 grams of 
the oil \^^th alcoholic potash, the soap mixture was neutrahzed with 
dilute acetic acid. The neutrahzed mixture was washed into a flask 
containing 25 cubic centimeters of water and 30 cubic centimeters of a 
20 per cent solution of lead acetate. After boihng,. the precipitated 
soap was cooled by immersing the flask in water and was agitated to 
cause the lead soap to stick to the sides of the flask. After decanting 
the water and excess of lead acetate and washing the adhering soap 
with water and 90 per cent alcohol, 50 cubic centimeters of ether were 
added and the mixture allowed to stand, after which it was heated for 
five minutes on a water bath with reflux condenser. The ether solu- 
tion of the soap was then cooled in a refrigerator over night and the 
insoluble soap allowed to crystaUize out. 

1 Official and provisional methods of analysis. Bulletin 107 (revised), Bureau of Chemistry, U. S. 
Dept. of Agriculture, 1910, p. 145. 
276 



FIXED OIL. 19 

To secure a separation of the solid fatty acids from the liquid 
acids, the method prescribed by the Association of Official Agricul- 
tural Chemists was again followed.^ After filtering the lead-salt 
mixture, the insoluble lead soap on the filter was washed into a flask, 
decomposed with hydrocldoric acid, and the mixture heated until the 
fatty acids melted. The flask was filled with hot water to bring ths 
melted acids into the neck, and then cooled. After decanting the 
water, the acids were again washed in a similar manner. The solid 
acids were finally dissolved in hot absolute alcohol and the solution 
allowed to evaporate. After drying and weighing, the amount of 
solid acids in the raisin-seed oil was found to be 8.4 per cent. 

The ether filtrate from the lead soap, which had been saved and 
which contained the lead salts of the liquid fatty acids of the oil, was 
placed in a separatory funnel and decomposed with 40 cubic centi- 
meters of a 20 per cent solution of hydrochloric acid. The precipi- 
tated lead cldorid was separated from the ether solution and the latter 
washed until free from acid. The ether solution of the liquid fatty 
acids was evaporated in an atmosphere of carbon dioxid to prevent th(>. 
oxidation of the acids. After evaporation of the ether, the amount 
of liquid fatty acids was found to be 84.7 per cent. 

SOLID ACIDS. 

The solid acids obtained by the above process appeared as a white, 
tallowlike, odorless, tasteless mass. The mixed solid acids after 
recrystallization melted at 57° to 58.5° C. By titrating a weighed 
portion of the solid acids with standard alcoholic potassium-hydroxid 
solution, 1 gram required 0.2163 gram of potassium hydroxid, which 
corresponds to a neutralization value of 216.3. Calculated from this 
neutralization value, the mean molecular weight of the solid acids 
is 259. 

The neutralization value and the mean molecular weight of the 
mixed solid acids would seem to indicate the presence of palmitic and 
stearic acids, inasmuch as palmitic acid has theoretically a neutrali- 
zation value of 219.1 and a molecular weight of 256, while stearic acid 
has a neutralization value of 187.5 and a molecular weight of 284. 
By comparing the thecrretical figures with those actually obtained, it 
appears that palmitic acid is considerably in excess of stearic acid. 
This is further partially substantiated by the fact that the melting 
point of the mixed acids is much lower than that of pure stearic acid, 
which melts at 69° C, and is even lower than that of pure palmitic 
acid, wliich melts at 62° C. As the mixed acids were recrystallized 
only once, the presence of traces of impurities would perhaps account 

1 Op. cit.,p. 142. 
276 



20 UTILIZATION OF WASTE EAISIN SEEDS. 

for the rather low melting point. Commercial stearic acid, which 
contains some impurities, is known to melt as low as 56° C. 

Taking advantage of the difference in solubility of these two acids 
in alcohol and hydroalcoholic solutions, a precipitation method was 
applied with good success. A small quantity of the mixed solid 
acids was dissolved in alcohol to a clear solution. The alcoholic 
solution was diluted with a small quantity of water, which produced 
a flocculent precipitate. This fraction was separate*d and dried. 
Another equal quantity of water was added to the filtrate, which 
produced a second precipitate, and this was likewise separated and 
dried. The neutralization value of fraction 1 was determined in the 
usual manner and was found to be 197.1, while that of fraction 2 
was 220.3. These values correspond very closely to stearic and pal- 
mitic acids, respectively. 

In order to ascertain the approximate proportion of the two acids 
in the mixture, a calculation was made from the mean molecular 
weight of the mixed acids, according to the method suggested by 
Lewkowitsch,^ which is as follows : 

Let X=percentage of palmitic acid, and Mj=molecular weight. 
Y== percentage of stearic acid, and M2=molecular weight. 
M=mean molecular weight obtained. 
X + Y = 100. 

M,X , M,Y_„ 
100 100 

Substituting the values of Mj, M2, and M in the formula, the follow- 
ing equation is obtained : 

256 X , 284 Y _ r,.Q 

To6- + Too~~''^^ 

Calculating the values of X and Y, the percentage of palmitic acid 
was found to be 89.3 and of stearic acid 10.7. A mixture of palmitic 
and stearic acids in the proportion of 90 to 10 actually gives a neutrali- 
zation value of 216.77 and a mean molecular weight of 258.8; hence, 
the percentages found indicate very closeh^ the proportion of these 
two acids in the mixed solid acids. 

Since 8.4 per cent of the original oil consists of solid acids, there is 
therefore 7.5 per cent of palmitic acid and 0.9 per cent of stearic acid 
in the oil. Since tlie oil consists of the glycerids of the fatty acids, 
it was necessary to reikice these percentages to terms of the corre- 
sponding glycerids. The glycerid palmitin contains 95.29 per cent of 
palmitic acid, and the glycerid stearin contains 95.73 per cent of 
stearic acid; therefore, making the calculations from the percentages 
of the free acids, it is found that raisin-seed oil contains 7.87 per cent 
of palmitin and 0.94 per cent of stearin. 

I Lewkowitsch, J. Chemical Technology and Analysis of Oils, Fats, and Waxes, vol. 1, 1909, p. 515. 
276 



/ 



/ 



FIXED .£. 21 

/ 

LIQUID ACIDS. 

The liquid acids of all fixed oils are usually unsaturated compounds 
with one or more double bonds in their molecular structure. Such 
unsaturated compounds possess the property of taking up oxygen, or, 
in other words, are readily oxidized, the compounds bemg changed 
into saturated hydroxylated compounds. In the case of the un- 
saturated fatty acids the resulting oxidation products are hydroxyl- 
ated acids, which are easily characterized and identified. 

Wlien an oil consists largely of liquid fatty acids, as is the case 
with raisin-seed oil, the composition of these liquid acids or their 
glycerids is essentially important, since it largely determines the 
value of the oil in its application to the arts and manufactures. For 
use in the manufacture of paint, the presence of certain fatty acids is 
required; for soap-making purposes certain other acids are necessary; 
and for use as an edible oil still others must be present. The liquid 
acids obtained from raisin-seed oil were of a golden-yellow color 
and bland, lardlike odor. The taste was fatty and bland, with a 
bitter aftertaste. The specific gi'avity at 25° C. was 0.9020 and the 
refraction at 25° C. was 1.4640. The neutralization value of the 
liquid acids was 199.8 and the iodin absorption value 146.1. 

Identification of the liquid acids. — In order to learn the composition 
of the mixed liquid acids obtained from raisin-seed oU, a small 
quantity of the acids was oxidized according to the method of Hazura 
and Griissner ^ by means of a H per cent solution of potassium per- 
manganate. Of the fatty acids 5 grams were neutralized with 6 
cubic centimeters of a 30 per cent solution of caustic potash. The 
resulting soap, after being dissolved in about 300 cubic centimeters 
of water, was oxidized with an equal volume of the potassium- 
permanganate solution, added gradually and with constant agitation. 
Sufficient sulphurous acid was finally added to dissolve the man- 
ganese compounds and to impart an acid reaction. The precipitated 
hydroxylated acids were then extracted with ether in successive 
portions to remove the ether-soluble dihydroxystearic acid, if present. 
The ether solution was evaporated and the crystals recrystallized 
from alcohol. The crystals melted between 134° and 137° C. and 
were therefore dihydroxystearic acid, which when pure melts at 
131.5° to 136.5° C. and is obtained by the oxidation of oleic acid. 

The acids which were insoluble in ether were boUed successively 
with water, several deposits of crystals being obtained. The crystals 
melted at 158° to 159° C, which corresponds to the melting point 
of an isomer of sativic acid (tetrahydroxystearic acid) obtained as an 

1 Hazura, K., aud Grussner, A. Zur Kenntnis des Olivenols. Monatshefte fiir Chemie, Bd. 9, 1888, 
p. 944. 

276 



V 



22 UTILIZATION C\ ASTE EAISIN SEEDS. 

oxidation product of linoleic acid. In addition to dihydroxystearic 
acid and tetraliydroxystearic acid a few crystals were obtaiiied which 
melted at 207° C. and which were probably hexahydroxystearic acid 
or liniisic acid, wdiich when ])ure melts at 203° to 205° C. The pres- 
ence of this oxidation product would seem to indicate that a trace of 
linolenic acid also exists in the liquid acids. 

The liquid acids of raism-seed oil apparently consist for the most 
part of oleic and linoleic acids, with a possible trace of linolenic acid. 
The neutralization value of 199.8 and the iodin absorption 146.1 of 
the liquid acids l:)oth point to the presence of oleic and linoleic acids, 
since the neutralization value of pure oleic acid is 198.9 and the iodin 
absorption 90.07, while linoleic acid possesses a neutralization value 
of 200.4 and an iodin absorption value of 181.4. 

The mean molecular weight of the liquid acids, calculated from the 
neutralization value 199.8, was found to be 280.78, which further 
supports the view that the acids consist mainly of oleic and linoleic 
acids, which have a molecular weight of 282 and 280, respectively. 
Using the equation given under solid acids and calculating from the 
mean molecular weight (280.78) for the determination of the propor- 
tions of oleic and linoleic acids present in the mixed liquid acids, it 
was found that linoleic acid predominates, being present to the extent 
of 61 per cent, while the remaining 39 per cent corresponds to oleic 
acid. 

These results were further confirmed by calculating the proportions 

of oleic and Imoleic acids from the iodin value of the mixed acids, which 

was 146.1. The iodin value of oleic acid is 90.07 and of linoleic acid 

181.42. Hence, letting X equal the percentage of oleic acid and Y 

the percentage of linoleic, the following equations are derived: 

X + Y = 100. 

90.07 X , 181 .42 Y .,.,., ,. t • ^ ■^^ 

— fnA~ + — inn = 1 (wuin absorption or mixed acids). 

Substituting the value of I and finding the values of X and Y, the 
results indicate that 61.3 per cent is linoleic acid and 38.7 per cent is 
oleic acid. 

It has been previously stated that 84.7 per cent of the original oil 
consists of liquid fatty acids. Assuming that the proportion of lino- 
leic and oleic acids in the liquid acids is approximately 61 and 39 per 
cent, the original oil contains about 51.7 per cent of linoleic and 33 
per cent of oleic acid. 

From these percentages the amounts of the glycerids linolein and 
olein can be calculated. It is know^l that linolein contains 95.67 per 
cent of Imoleic acid and olein contains 95.7 per cent of oleic acid. 
Hence, calculating by simple proportion, it is found that the oil con- 
sists approximately of 54 per cent of linolein and 34.48 per cent of 
olein. 

276 



FIXED V ^. 23 

Briefly summarizing the results obtained from the chemical exami- 
nation of raisin-seed oil, the following composition is indicated: 

Per cent. 

Linolein 54 

Olein 34. 48 

Palmitin 7. 87 

Stearin 94 

Free acids (calculated as oleic acid) 62 

The remainder of the oil consists of small amounts of volatile acids, 
soluble acids, and unsaponifiable matter, with possibly a trace of the 
glycerid of linolenic acid. 

DRYINCJ PROPERTY OF RAISIN-SEED OIL. 

Since the fixed oil of raisin seeds contains constituents with drying 
properties, it was thought advisable to determine the actual drying 
value in order to compare it with some of the standard drymg oils. 
The drying property of a fixetl oil depends upon its power to absorb 
oxygen and it must necessarily contain constituents which are readily 
oxidizable. This property is also greatly influenced by the condition 
of the oil. In the raw condition, untreated in any way, oils usually 
possess the power of oxygen absorption to a much less degree and with 
much less rapidity than when subjected to certain treatments, such 
as boiling or heating with compounds rich in oxygen. Simple con- 
tinued heating of an oil modifies this property of oxygen absorption, 
rendering the oil more powerful in this respect. The most common 
method, perhaps, of rendering oils more susceptible to the absorption 
of oxygen is treatment with the so-called "driers." Common among 
these are lead oxid (litliarge), manganese dioxid, and a combination 
of manganese with rosin known as manganese rosinate. 

In order to determine the drying property of raisin-seed oil, the 
crude raw oil was treated first by heating for 30 minutes at 200° to 
210° C; second, by heating for 15 minutes at 190° to 200° C. with 
lead oxid varying in quantity from one-half of 1 to 4 per cent; and, 
third, by heating for 15 minutes at 190° to 200° C. with manganese 
dioxid varying in quantity from 1 to 4 per cent. A sample of raw 
linseed oil, chosen for the purpose of comparison, was treated in the 
same manner. 

As has been stated, the drying of oils is accompanied by the absorp- 
tion of oxygen. There results, therefore, an increase in weight and 
the percentage of this increase determines the drying quality of the 
oil. Although some oils when exposed to the air gradually absorb 
oxygen and become dry, yet the less the quantity the more rapid the 
process, and in order to complete the experiments as rapidly as pos- 
sible they were carried out in the following manner: Thin layers of 
the prepared oils, ranging in weight from 12 to 14 centigrams, were 

276 



24 



TTTTLIZATTOlSr (\ ,VASTE EAISIN SEEDS. 



spread evenly over small glass plates having an area of 25 square 
centimeters. The plates were then set aside in a place free from dust 
but with free access of air. They were carefully weighed from time 
to time and the percentage of increase computed. The weighings 
were conducted over a period covering the time required in each case 
for the maximum absorption, the period varying with the different 
samples and the different treatments. The results are given in 
Table I. 

Table I. — Oxygen absorption, or percentage of increase in weight, of films of raisin-seed 
and linseed oils when treated in various ways. 





Raw. 


Heated. 


Heated with PbO. 


Heated with MnOj. 


3 

8, 


'S 

c 


o 


o 

T3 

•i 

P3 


'o 

3 


One-half 
of 1 per 
cent. 


1 percent. 


2 per cent. 


4 per cent. 


1 percent. 


2 per cent. 


4 percent. 




.So 


o 
-a 


■a 

•3 


o 
■d 

a 


t3 
1 . 
1° 


'3 

1 

2 


'3 


'o 

p 
3 


•a 
'3 


'3 
■a 

3 


M 
■3 


"3 
% 

a 

3 


§ 
■3 


"3 
3 


Hours . 
5 


P.ct. 


P.ct. 


r.ct. 


p.ct. 


p.ct. 

1.7 


p.ct. 
2.29 


P.ct. 


p.ct. 


P.ct. 


P.ct. 


p.ct. 


p.ct. 


p.ct. 


P.ct. 


p.ct. 
0.3- 


p.ct. 
0.29 


P.ct. 

0.07 


P.ct. 


6 







0.24 


0.23 


5.1 


7.8 


5.7 


9.3 


2.8 


9.8 


22 




















23 










6.76 


11.6 


8.4 


13.3 


8.4 


12.8 


7.6 


12.0 














24 




(') 


.32 


.47 


(') 
(') 
(') 

0.23 
.63 
1.1 


?! 

0.94 
3.6 
10.7 


.3 
.3 
..37 
.52 

.82 
1.7 


.43 
1.3 
8.1 
13.7 
1.3.9 
1.3.9 


.13 

.47 

.54 

1.5 

2.4 

3.8 


7.3 


29 






8.8 
8.8 
8.8 
8.2 
7.7 


13.7 
13.7 
13.5 
13.3 


8.78 

8.2 

8.1 

7.2 

7.2 


13.0 
1.3.2 
13.0 
12.8 
12.8 


8.2 
7.3 
7.3 
6.4 
6.2 


12.0 
12.2 
11.9 

ll!7 


9.9 
13.7 
13.9 
13.7 
13.5 


48 

72 

90.. 






.4 

.4 

1.2 

2.0 


.47 
.47 

1.1 

1.66 


8.67 
9.12 
8.6 
8.0 


13.2 
13.2 
13.2 
12.7 


120.... 
144.... 


0.24 
.4 
.65 


(') 
(') 
(') 

0.70 
3.3 

7.8 


168.... 
192.... 


5.87 
8.52 
10.6 
9.7 
9.1 
8.76 


8.4 
13.1 
14.1 
13.4 
12.9 
12.6 


6.4 


12.6 


7.1 




6.66 


12.6 


6.0 


11.7 


4.64 
6.7 
8.5 
9.3G 
10.0 
9.9 


14.0 
13.5 
13.3 


5.0 
7.26 
8.83 
9.58 
10.0 
9.73 


12.9 
12.3 
11.2 


8.29 
9.99 
9.92 
9.79 
9.38 
8.85 


13.0 
12 7 


210.... 






6.1 




5.9 


11.6 


.5.4 


11.4 


12 1 


240. . . . 








264.... 


















288.... 


1.95 
2.75 
4.53 
6.88 
8.43 
9.32 


14.1 
13.1 
12.4 
11.1 
10.6 
10.6 




1 














312.... 




1 














336.... 








j 












8.88 




8.84 




8.1 




360.... 


7.0 


11.7 




1 














384.... 




1 






















408.... 












[ 


















432.... 






i i 






















456.... 
































480. . . . 


7.1 


9.6 


















































1 



1 No increase. 

An analysis of the table shows that the raw oils absorbed oxygen 
very slowly, both oils beginning absorption at about the same time. 
The percentage of increase, however, was much more rapid from 
hour to hour in linseed oil than in the oil from raisin seeds. The 
latter attained its maximum absorption in 408 hours, a total of 9.32 
per cent of oxygen being absorbed, while the linseed oil reached its 
limit in 288 hours, with a total oxygen absorption of 14.1 per cent. 
Both films were dry but gelatinous, the raisin-seed oil film being a 
trifle more sticky than that of the linseed oil. 

The heated oils absorbed oxygen much more quickly than the raw 
oils. An increase in the weight was noted at the first weighing in 6 

27G 



FIXED OIL. 25 

hours. The increase was steady and considerably more rapid than in 
the raw oils, the maximum in both oils being reached in 216 hours. 
The percentage of absorption was practically the same as in the raw 
oils, but the time of absorption was less in the raisin-seed oil, the 
heating, therefore, having the eflFect of hastening the drying. 

The experiments show also that by heating the oils with lead oxid 
in quantities varying from one-half of 1 to 4 per cent, oxygen was 
absorbed with much greater lapidity than by the heated or raw oils. 
When heated with 1 and 2 per cent of leatl oxid the films had practi- 
cally become set in 6 hours, the absorption in raisin-seed oil amount- 
ing to 5.1 and 5.7 per cent, respectively, and in linseed oil to- 7.8 and 
9.3 per cent, respectively. Each of the oils treated with the varying 
quantities of lead oxid produced a film which at the end of 23 hours 
was dry, with only a slight stickiness. The maximum absorption in 
the case of raisin-seed oil was 8.1 to 9.12 per cent, and in linseed oil 
12.2 to 13.7 per cent, which was about the same range. \Mien heated 
with 4 per cent of lead oxid there was less total abso-ption in both 
oils than when heated with one-half of 1, 1, and 2 per cent. Appar- 
ently the oils heated with 1 and 2 per cent tlried most rapidly in each 
case. 

Manganese dioxid seemed to be much less efficient as a drier than 
the lead oxid, the length of time necessary to dry the films being in 
all cases considerably longer than when the oils were heated with 
lead oxid. Four per cent of manganese dioxid appeared to be the 
most favorable, the films of both oils drj-ing more rapidly than when 
containing a less quantity. The maximum oxygen absorption of 
raisin-seed oil (9.99 per cent) was not reached until 192 hours, while 
linseed oil required only 72 hours, the total absorption being 13.9 
per cent. Both the raisin-seed and linseed oils when heated with 
manganese dioxid produced films of about the same texture, drying 
to about the same degree of liardness as with the lead oxid. 

In texture and tenacity the films in all the experiments bore a 
close resemblance, those of linseed oil being a trifle harder and a 
little less sticky than those of the raisin-seed oil. All were trans- 
parent and somewhat elastic and insoluble in ether. In all the 
experiments there seemed also to be a continual decrease in weight 
after the maximum absorption had Vjeen reached, the films becoming 
harder and less sticky. 

COMPARISON OF RAISIN-SEED OIL WITH OTHER DRYING OILS. 

Since only unsaturated fatty acids possess the property of taking 
up oxygen, this class of constituents is necessary to drying oils. 
Stearic acid is a saturated fatty acid and does not change on exposure 
to air. Oleic acid, on the other hand, contains two atoms of hydrogen 
less than stearic acid and is a common unsaturated fatty acid present 

276 



26 UTILIZATION OF WASTE EAISIX SEEDS. 

in many fixed oils. Tliis acid, therefore, readily takes up oxygen. 
Saturated and unsaturated fatty acids are usually present in oils in 
combination with glycerin and are known as glycerids. These 
glycerids in the cases of some of the more common fats are knowTi 
as olein, palmitin, and stearin. 

Most dr^dng oils contain constituents in conunon u})on which the 
drying property depends. The most important of these constituents 
are the gh'cerids of linolenic and linoleic acids. These compounds 
absorb oxygen from the air very readily, forming a neutral com- 
pound kno^^Tl as linoxyn, which is the characteristic end product of 
all drying oils used in paints and varnishes. This property of 
oxygen absorption is sometimes called autoxidation. AMien exposed 
to the air, drying oils will oxidize, the time required for complete 
oxidation, or formation of linoxyn, depending upon the nature of the 
oil and the thickness of the layer exposed. Tliis oxidizing property 
is favorably influenced when certain substances known as siccatives 
or driers are digested with the oil. Metallic oxitls, such as lead oxid 
and manganese dioxid, antl such salts as manganese and lead resinates 
are commonly employed siccatives. WTien oils are digested with 
any of these compounds the change of the unsaturated acids to 
linoxyn is considerably hastened, the siccatives, in a catalytic way, 
bringing about more rapid absoiption. This is clearlv shown in 
Table I. 

Among the dr^Tiig oils the most important arc luiseed, walnut. 
China-wood (tung), hempseed, sunflower, and poppy-seed oils. Those 
most commonly used in this country are Imseed and China-wood 
oils. Lmseed oU is the only one produced in the United States and 
occupies a foremost position as a paint oU. The liquid constituents 
of the drying oils mentioned contain either linolenic or Imoleic acids, 
or isomerids of these acids, the acids occurrmg in combmation with 
glycerm as glycerids. Oleic acid in the form of its gh'cerid, olein. is 
also a constant constituent of these oils. The linoleic and linolenic 
acids, however, are of chief concern from the standpoint of the use- 
fuhiess of the oUs in the manufacture of paints and varnishes. 

The experiments recorded in Table I show that the maximum 
absorption of raisin-seed oil was 10.6 per cent, while that of linseed 
oil was 14.1 per cent. In both cases the figures were obtained from 
experiments conducted with the heated oils. \Mien siccatives were 
employed the maximum absorption was not increased, but the opera- 
tion was greath' hastened. This has also been shown b}' Lippert/ 
who experimented with lead oxid (litharge) and manganese resinate 
as driers. Linseed oil was heated to 150° C. for 15 minutes Avith 

iLipperl, Walther. Zur Krmittelunsj der von trooknenden Oelen vmd Fimissen absorbirten Sauer- 
stoflmenge. Zeitschrift fiir Angewandte Chemie, 1898, Heft 19, p. 431. 



FIXED OIL. 



27 



varying percentages of driers, the weight of the film bemg from 0.11 
to 0.13 gram ])or 100 square centimeters. The following results 
were recorded: 

Table II. — Oxygen absorption of Unseed oil when heated uith manganese resinate and 

lead oxid. 



Heated with- 



Gain in weight after- 



12 hours. 



23 hours. 



36 hours. 



39 hours. 



Remarlcs. 



Manganese resinate: 

6.02 percent 

0.06 per cent 

0.15 per cent 

0.2 per cent 

Lead oxid: 

0.34 per cent 

1.1 percent 

2.5 percent 

6.8 per cent 



Per cent. 
2.1 
4.89 
.6.6 
6.46 



Per cent. 



Per cent. 
15.97 
15.48 
14. 45 

14. 02 



Per cent. 



17 per cent in 55 hours. 
15.69 per cent in 40 hours. 



8.5 
13.5 
12.7 
12.3 



11.1 
13.9 



The experiments with raisin-seed oil heated with lead oxid seem 
to bear out Lippert's conclusion that the use of driers beyond a 
certain percentage produces no appreciable difTerence in the absorp- 
tive power. In both raisin-seed and linseed oils (Table II) the use 
of more than 1 per cent of lead oxid mdicated no increase in the 
absorptive power, the films being practically dry in 23 hours with 
almost the maximum of oxygen absorption. The use of more than 
1 per cent of manganese dioxid also seems to have no distmctly 
favorable influence uj)on the drying of the films of either raisin-seed 
or linseed oil. 

A number of fixed oils have been investigated by Weger ^ and Kuhl ^ 
with respect to their oxygen-absorption properties and for the sake 
of comparison with raisin-seed oil are here given: 

Table III. — Oxygen-absorption power of certain drying oils. 



Kind of oil. 



According to Weger. 



According 
to Kuhl. 



Linseed (foreign) . 

China wood 

Hempseed 

Poppy seed 

Sunflower 

Walnut 

Rapeseed 

Olive 

Peach kernel 



Per cent. 
18 
14-16 
13,5 
13.4 



7.6 
5.2 
10.5 



Days. 
"3-7 
3-8 
4-4i 
64 



Per cent. 
17.5 



16.8 
15.6 
14.8 
19.6 



These results show that the foreign linseed oil possesses a greater 
power of oxygen absorption than the American linseed oil, which was 

1 AVeger, Max. Ueber die SauerstofEaufnahme der Oele und Harze. Chemische Revue fiber die Fett- 
und Harz-Indu.strie, Jalu-g. 5, 1S98, p. 249. 

2 Kuhl, Dr. Die Firnisbildung der Oele. l^harmazeutische Zentralhalle, Jahrg. 51, 1910, p. 185. 

276 



'28 UTILIZATION OF WASTE EAISIN SEEDS. 

used in the experiments previously discussed. It will be seen by 
carefully comparing raisin-seed oil with the oils mentioned that 
although it possesses drjring properties somewhat lower than such 
standard oils as Imseed, China wood, and walnut, yet it has good 
drjong properties as compared with the other drying and semidrying 
oils. 

RAISIN-SEED OIL AS A PAINT AND VARNISH OIL. 

Taking into consideration the ready-drying proi)erty of raisin-seed 
oil, especially when treated with an ordinary drier such as lead oxid, 
it should be of value in the paint and varnish industries. Not only 
does the oil when treated with driers absorb oxygen rapidly, but it 
compares favorably with linseed o'A m this respect. Granting, 
however, that linseetl oU absorbs oxygen more rapidly, the nature 
of the films after drymg is much the same, both being transparent 
and elastic. The linseed-oil film difi'ers apparently only in bemg 
slightly less tacky. 

In order to ascertain its value as a paint oil, a small quantity of 
the oil was submitted to a paint manufacturer for a practical test. 
Two kinds of paint were made up, one being an oxid red and the 
other a graphite. The oxid-red paint was made the same as with 
Imseed oil. The vehicle of the pamt was composed of 8 parts of 
raism-seed oU, 1 part of spirits of turpentine, and 1 part of linseed 
oil and gum japan. The driers used in the japan were litharge and 
oxid of manganese. The base of the paint was red oxid. 

The paint was found to be of the same usual body as linseed-oil 
paint and flowed nearly as well under the brush. It dried somewhat 
more slowly but produced a high-gloss finish. Red oxid was chosen 
because this particular oxid is known to be very destructive to lin- 
seed oil, the color quickly losing its brilliancy and the paint becoming 
dead and bluish purple. 

After four months' exposure, from August to December, the paint 
prepared with raisin-seed oil had a fme film with a good finish and 
the oxid was still as brilliant as when applied, which was exactly con- 
trary to the results obtained with the linseed-oil paint. In August a 
sample of the paint was applied to corrugated iron on the south side 
of a building exposed to the strongest sunlight in a smoky district 
adjacent to blast furnaces which continually gave off gases. In 
March, after seven months' exposure to these conditions, the paint 
still retamed the true, perfect color of the oxid and the finish was 
intact. In the opinion of the manufacturers, this particular paint 
"stood u])" very well, far better in fact than linseed-oil ]iaint under 
the same conditions. 

Raisin-seed oil is decidedly resistant to heat and declines to take 
on color even when heated to 500° F., whereas linseed oil darkens 
276 



FIXED OIL. 29 

considerably and takes on a greenish color. The somewhat slower 
drying ])roperties oi" raism-seed oil should not be especially detri- 
mental to its usefulness, since this can doubtless be overcome by 
treatment of the raw oil with proper driers. The preliminary experi- 
ments have show^n that it can be used in the manufacture of paint, 
and in the particular instance mentioned it acted better than linseed 
oil. 

Since raisin-seed oil acts so well in the manufacture of pamt it 
could unquestionably be used also with equal success in the manufac- 
ture of varnish, in which at present linseed and China-wood oils are 
used almost entirely. 

As raisin-seed oil contams a large quantity of linoleic acid, together 
with some linolenic acid, it should also be capable of being oxidized 
to produce what are commonly known as oxidized or blown oils. 
These are drying or semidrying oils which have been artificially 
oxidized by heating in a current of air or oxygen and find extensive 
use in the various industries. It is probable that by the oxidation of 
raisin-seed oil there would result a substance similar to that formed 
from linseed oil (linoleum mass) which is used so extensively as a 
basis for makmg linoleums. 

RAISIN-SEED OIL AS A SOAP-MAKIXG OIL. 

For the purpose of testing the usefulness of raisin-seed oil in the 
manufacture of soap, a small quantity was saponified by the "cold 
process" with a calculated amount of strong sodium-hydroxid solu- 
tion (about 30 ])er cent), the alkali being slightly m excess of the 
amount required to exactly saponify the given weight of oil. After 
standing 24 hours the excess of water was separated from the mass 
and the soap pressed hito a cake and allowed to dry. A hard, com- 
pact soap resulted, which after several months still retained its white 
appearance, with only a trace of discoloration. Although this small 
quantity was made in a very crude way, yet, to all outward appear- 
ance at least, the sample, which produced a copious lather, showed 
that raisin-seed oil has some of the qualities of a soap oil. 

This favorable prelimmary test caused a desire to obtain the judg- 
ment of practical soap makers regarding the merits of the oil as a soap 
material. Accordingly, a sample of the fixed oil was submitted to a 
prominent soap manufacturer for a practical test. The soap chemist 
described the oil as being fair in color, but causing a somewhat deeper 
coloration upon saponification than some of the first-class soap oils. 
It was stated, however, that this could easily be removed by repeat- 
edly salting out. It was also suggested that a process of refining or 
bleaching would remove the objectionable color and make it very 
suitable for use in the soap industry. 

276 



30 UTILIZATION" OF WASTE KAISIN SEEDS. 

The soap was described as being about equal to olive-oil soap in 
color and as having a pleasant aromatic odor. Since the oil contains 
only a small percentage of palmitin and stearin, it was suggested that 
it could be used advantageously in the manufacture of toilet soaps in 
connection with tallow, palm oil, or coconut oil, which would have a 
tendency to produce a firmer soap with a higher meltmg point. 

The fixed oils best adapted to the manufacture of fancy soaps are 
olive oil, ])alm oil, coconut oil, and almond oil. The latter, owing to 
its scarcity, is not used except for special purposes. Oils with high 
saponification value, such as coconut and palm oils, are used in con- 
nection with animal fats in order to increase their solubility and the 
lathermg ])r()})erties of the soap. Olive oil, which is much used in the 
manufacture of the finer grades of soaps, has a saponification value 
only slightly higher than raisin-seed oil. 

It appears, therefore, from the tests conducted, that the oil of raism 
seeds possesses qualities which should make it of considerable value 
in the soap industry. 

AVAILABLE QLTANTITY AND VALUE. 

After removing the sugary matter for the preparation of the sirup 
there was found to be a reduction of about 20 ])er cent in the total 
weight of the seeds. Therefore, the weight of the seeds remaining 
would be from 2,400 to 3,200 tons. The average yield of oil being 
about 14.5 })er cent, the total quantity of oil capable of being manu- 
factured from this material would be approximately from 348 to 464 
tons. Calculating from the specific gravity of the oil, this represents 
from 90,390 to 3 20,520 gallons available annually. 

As a paint oil the value of the yearly production should approximate 
$35,000 to $50,000. In the manufacture of soap its value would per- 
il a j)s be somewhat less, 

TANNIN. 
EXTRACTION. 

In order to separate the tannin from the seeds after the extraction 
of the fixed oil, 1 kilogram of the residue was boiled out repeatedly 
with water and the aqueous extract evaporated. After evaporation 
there resulted 292 grams, or 2.92 per cent, of a semisolid extract, with 
a deep reddish brown color and a strong astringent taste. The moist 
extract contained 43.5 per cent of water; therefore, there would be 
16.5 per cent of dry extract available. The dry extract was deep 
brownish red in color, breaking with a glassy fracture and having the 
odor of licorice. 

ANALYSIS. 

Upon analysis the dry extract was found to contain 28.38 per cent 
of tannins. , Nontannins were present to the extent of 60.82 per cent. 

276 



TANNIlSr. 31 

The total amount of soluble solids was 89.2 per cent and of the 
insoluble material 10.8 per cent. 

According to Trimble, tannins are divided into two general classes, 
known as the gallotannic-acid group and the oak- tannin group, the 
former including such tannms as are found in nutgall, chestnut bark, 
pomegranate bark, and sumac, wliile the latter group includes oak^ 
mangrove, kino, canaigre, etc. The two groups are characterized by 
their behavior toward certain reagents, such as lime water, bromin 
water, and ferric chlorid. In order to determine the class to wMch 
raisin-seed tannin belongs, tests were made with these reagents. 
With lime water a reddish precipitate resulted, with bromin water a 
yellowish turbidity, and with ferric clilorid a green coloration was 
produced. These tests would place the extract in the oak-tannin 
group, since the same reactions are produced with oak tannins, while 
the gaUotannic-acid group produces a blue j)recipitate with lime 
water, no reaction wdth l)romin water, and a l^lue precipitate with 
ferric chlorid. 

DYE STUFF. 

In extracting the tannin considerable reddish coloring matter was 
also extracted. Although this coloring matter may be of no great 
unportance as a dyestuff, its })rescnce may add to the usefulness of the 
extract, since tanners often desire a coloring matter in connection 
with tanning extracts. Therefore, an examination was made as to its 
coloring properties. 

As part of the coloring matter still remained in the residue after 
the extraction of the tannin, a small quantity of this residue was 
heated on a water bath with a 1 per cent solution of sodium hydroxid 
in successive portions. The deep purple-red solution was decanted 
and filtered in each case and neutrahzed with sulphuric acid. The 
dyestuff was precipitated in the form of a reddish brown flocculent 
mass, wliich was filtered, dried, and ground to a powder. In this 
manner about 18 per cent of a brownish red dyestuff was obtained, 
wliich was found to be readily soluble in dilute aqueous alkah to a 
purple-red color. In dilute acids it was less soluble, a yellowish 
coloration resulting. The powder was soluble in hot water to a 
brownish red solution. It was almost insoluble in ether, chloroform, 
and benzene, but was readily soluble in methyl alcohol to a red 
solution. It was somewhat less soluble in ethyl alcohol to a Hght 
brownish solution. 

To test its properties as an indicator a smaU amount of the dye 
was dissolved by means of a few drops of tenth-normal sodium 
hydroxid and the purple-red solution diluted with water until the 
color was stiU distmguishable. Upon the addition of standard acid 
solution drop by drop, a sharp end reaction was noted, the change 
from purple red to yellow being readily seen. An aqueous solution, 

276 



32 UTILIZATION OF WASTE KAISIIST SEEDS. 

when treated with mordant reagents, reacted l^y giving precipitates 
as follows: 

Potassium bicliroiiiate - Brownish red. 

Ferrous sulphate Brownish red. 

Stannous chlorid '. Bright red. 

Copper sulphate Dirty brown. 

Alum Pale brownish red. 

Zinc sulphate Dark red. 

After precipitating the dye from its alkahne solution by neutraUzing 
with acid, the filtrate still possessed a reddish color, and after being 
evaporated down to about one-half its volume it was deep brown red 
in color. A small strip of cotton cloth was introduced into this 
solution and heat applied for about two hours, after which the cloth 
had taken on a deep-brown color. The dyed cloth was then mor- 
danted with alum, after which it was dried and thoroughly washed 
with soap and water. After washing several times the cloth had a 
brownish red color, practically identical with that of the dyestuff. 

Usually a variety of shades can be produced with a dye by means of 
different mordants. In order to ascertain the range of shades possible 
with the different metaUic mordants, a crude dyeing experiment was 
carried out. The mordants chosen were chromium, iron, tin, copper, 
aluminum, and zinc. After immersing narrow strips of cotton cloth 
in the mordant solution for several hours they were transferred to 
neutral solutions of the coloring matter in question and heated for 
several hours, after which the strips were again immersed in the 
mordant and finally washed. The following shades were produced 
with the various mordants: 

Potassium Inchromate Pale lirownish \'iolet. 

Iron sulphate (ferrous sulphate) Grayish Adolet. 

Tin chlorid (stannous chlorid ) Tight red. 

Copper sulphate Reddish violet. 

Alum (aluminum-potassium sidphate) Brownish red. 

Zinc sulphate Light violet red. 

It is very difficult to satisfactorily describe the shades produced, 
but distinct differences in color were apparent. 

While the coloring matter or dyestuff may possess no direct value 
as a dyeing agent because of the cheaper and more available coal- 
tar dyes, it has been discussed principally for the reason that the 
tannin extract contains a considerable quantity of this substance 
and under the skillful mani])ulation of the tanner and the dyer it may 
be possible to produce tans of variable shades by the use of the differ- 
ent mordant solutions. 

USE OF THE EXTRACT IN TANNING. 

Partially to satisfy a desire to know whether the extract would be 
serviceable in the tanning of leather, a small quantity was submitted 

276 



MEAL. 33 

to a commercial tanner for a practical test. The sample of leather 
tanned with the extract was fairly good in all general appearances. 
It was light reddish brown in color and was quite soft to the touch. It 
can not be said here whether tliis extract will compare favorably with 
some of the more common extracts, but from the test made and from 
the fact that it belongs to a class of tannins wliich are extensively 
used it does not seem unreasonable to suppose that it may find 
use in the leather industry, since a brisk and steady demand for 
tanning materials now exists. 

AVAILABLE QUANTITY AND VALUE. 

The quantity of seeds remaining after the removal of the pulp 
for the sirup and the extraction of the fixed oil would approximate 
2,000 to 2,700 tons. This material is directly available for the 
preparation of tannin extract and as much as 16.5 per cent may be 
extracted from it. The total weight of dry tannin extract, therefore, 
wliich could be prepared is about 330 to 445 tons, or from 660,000 to 
890,000 pounds annually. The value of the yearly output of this 
extract, roughly estimated, should be from $19,000 to $26,000. 

MEAL. 

The residue left after the extraction of the fixed oil and the tannin 
extract has been termed the meal and constitutes the greater portion 
of the by-product. It consists largely of protein, carbohydrates, 
and inorganic constituents, of which possibly the protein is of most 
importance. According to analysis the meal contains 1.94 per cent 
of nitrogen, which corresponds to 12.12 per cent of available protein. 
Other constituents have been determined as follows: Moisture 10.6 
per cent, ash 2.4 per cent, crude fiber 43.2 per cent, nitrogen-free 
extract 30.5 per cent, and ether extract 1.2 per cent. 

VALUE AS STOCK FOOD. 

The utilization of the meal lies in its possibility as a stock food. 
The valuable constituents in stock foods are protein, carbohydrates, 
and mineral comi)ounds. The protein comprises the nitrogen com- 
pounds present and is most essential for the formation of the nitrogen 
tissues and for the proper growth of the animal. Protein compounds 
are contained to a greater or less extent in practically all vegetable 
and grain foods which are used for stock feeding. The carbohydrates, 
in which are included crude fiber, starch, sugar, and gums, are also 
most essential as feeding stuffs and are present in all vegetable stock 
foods in varying proportions. The crude fiber or cellulose is present 
in large quantities in such feeding stuff as hay, straw, bran, and in 
the hulls of the various grains. Cellulose, while digested with diffi- 
culty, is considered to possess food value. The nitrogen-free extract 

276 



34 



UTILIZATION OP WASTE BAISIN SEEDS. 



embraces starch, sugar, and some gums whose nutritive values are 
generally conceded. Practically all stock foods of value contain 
large percentages of nitrogen-free extractive which is readily digested 
and assimilated by the animal. Like the soluble carbohydrates, the 
ether extract or fat is an important fuel and fat-producing constituent 
of stock foods. Likewise, the mineral portion, or ash, of vegetable 
foods is also a necessary ingredient. 

For the purpose of comparing the composition of raism-seed meal 
with other stock foods, the following table has been compiled. Only 
four classes of stock foods are given, namely, hay, straw, grains, and 
hulls, as these most nearly correspond to the class of foods to which 
raisin-seed meal is most closely related. The figures represent the 
relative composition of the foods as given by Jordan.^ 

Table IV. — Comparison of raisin-seed meal with various feeding stuff's. 



Feed. 











Nitrogen- 


Moisture. 


Ash. 


Protein. 


Fiber. 


free 
extract. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


10.6 


2.4 


12.1 


43.2 


30.5 


10.7 


1.4 


2.4 


30. 1 


54.9 


7.3 


6.7 


3.3 


29.7 


52.1 


8.2 


13.2 


3.6 


35.7 


38. 6 


13.2 


2.2 


4.6 


43.5 


35.3 


11.1 


2.8 


4.2 


46.3 


33.4 


9.0 


3.4 


6.6 


64.3 


15.1 


9.2 


5.1 


4.0 


37.0 


42.2 


7.1 


3.2 


3.0 


38.9 


46.6 


9.6 


4.2 


3.4 


38.1 


43.4 


10.1 


5.8 


4.6 


40.4 


37.4 


13.2 


4.4 


5.9 


29.0 


45.0 


11 6 


6.7 


7.2 


26.6 


45.9 


8.4 


7.4 


14.3 


25.0 


42.7 


11.0 


3.0 


11.8 


9.5 


59.7 


10.9 


2.4 


12.4 


2.7 


69.8 


11.6 


1.9 


10.6 


1.7 


72.5 


10.5 


1.8 


11.9 


1.8 


71.9 


10.9 


1.5 


16. 5 


2.1 


59.6 


12.6 


2.0 


10.0 


8.7 


64.5 


8.6 


2.6 


16.3 


29. 9 


21.4 


10.3 


3.5 


18.4 


23.2 


24.7 



Ether 
extract. 



Raisin-seed meal 

Corn cobs 

Oat hulls 

Rice hulls 

Buckwheat hulls 
Cottonseed hulls. 

Peanut hulls 

Oat straw 

Rye straw 

Wheat straw 

Soy-bean straw . . 

Timothy hay 

Swamp hay 

Alfalfa hay 

Oats 

Barley 

Rye 

Wheat 

Corn 

Buckwheat 

Sunflower seeds. 
Cotton seeds — 



Per cent. 
1.2 

0.5 
1.0 
0.7 
1.1 
2.2 
1.6 
2.3 
1.2 
1.3 
1.7 
2.5 
2.0 
2.2 
5.0 
1.8 
1.7 
2.1 
5.4 
2.2 
21.2 
19.9 



From a careful observation of the table it is evident that the 
moisture content of raisin-seed meal is much the same as in the vari- 
ous foods cited. In percentage of ash it corresponds more closely to 
the grains and is much the same as the hulls, with the exception of the- 
rice and oat hulls. It is lower in ash content than the various hays 
and straws. In protein it greatly excels the hulls, hays, and straws, 
containing practically the same amount as the various grains. The 
high percentage of protein as compared with the various hays and 
straws should make the meal of considerable food value. The percent- 
age of fiber is relatively high, while the nitrogen-free extract compares 
with that of the grain hulls mentioned. Since the meal contams 



276 



» Jordan, W. H. The Feeding of Animals, 1909, pp. 425-426. 



SUMMAEY. 35 

about 30.5 per cent of nitrogen-free extractive it is fairly rich in 
soluble carbohydrates, which are of importance as a nutritive food. 
The ether extract or fat of the meal compares favorably with that of 
the hays, straws, and grain hulls. 

Since raisin-seed meal contains considerable protein, together with 
a fairly high content of ash, soluble carbohydrates, and fat, it should 
possess useful feedmg value. If mixed with other foods to supply 
the deficiency of some of its constituents, a well-balanced ration for 
the feeding of stock could be made and the meal thus profitably 
utilized. It should also be of some value as a constituent of chicken 
feed, since considerable protein is required in chicken rations. , 

AVAILABLE QUANTITY AND VALUE. 

After the extraction of the tannin and the fixed oil from the raisin 
seeds there would remain about 1,600 to 2,200 tons of meal. The 
annual output of the meal, roughly estimated for its stock-feeding 
value, would be approximately from $16,000 to $23,000. Its feeding 
value would, however, necessarily have to be determined by actual 
feeding experiments. 

SUMMARY. 

In the preceding pages it has been shown that four important 
commodities, namely, sirup, fixed oil, tannin extract, and meal, are 
capable of being made from the large quantities of grape and raisin 
seeds which result from the seeding of raisins and the manufacture of 
wine and grape juice in this country. 

Commercially, the manufacture of the sirup could be accomplished 
with comparative ease and readiness. Owing to the solubility of the 
sugars in water, the process of preparation resolves itself into simple 
extraction and concentration. Comparatively small quantities of 
water are necessary to completely dissolve the sugary matter from the 
seeds. Tlie washing could possibly be most readily accomplished in 
large centrifuges, while the saturated solution requires only to be 
evaporated to produce the sirup. As the most convenient form of 
concentrating, vacuum pans would be the most efficient and 
expedient. 

A clear, transparent sirup, with the characteristic delightful taste 
and flavor of the raisin, can be produced from the sticky seeds. Its 
uses are many and should justify its production from this waste 
material. 

The fixed oil has been mentioned as found in considerable quan- 
tity in the seeds of raisins and also in the seeds of grapes which 
occur as by-products in the manufacture of wine and of grape juice. 
After washing off the sugary matter and drying and screening the 

276 



36 UTILIZATION OF WASTE EAISIN SEEDS. 

seeds, they need only to be ground for the production of the fixed oil. 
Two methods of extraction are feasible — by pressure and by solvents. 
Hot extraction by means of hydraulic presses would possibly yield the 
maximum of fixed oil. Cold pressure, having a tendency to incom- 
pletely extract the oil, would leave more fat in the press cake. 
Extraction by means of solvents such as benzene, carbon bisulphid, 
or low-boiling gasoline, or preferably, carbon tetrachlorid or trichlore- 
thane, is practiced commercially because of the more complete 
exhaustion than by pressure, especially of materials with low oil 
content. The use of carbon tetrachlorid and trichlorethane has been 
recommended because of the noninflammable, nonexplosive properties 
of these solvents, both of which have comparatively low boiling 
points and are easily recovered. They are also capable of being used 
again for the same purpose. 

The clear, amber-colored fixed oil, useful in paint and soap manu- 
facture, and possibly in other industries, is capable of being produced 
in large quantities from the waste seeds. The important application 
of the* oil in commerce, coupled with the large output aA^ailable 
annually, should justify its production. 

After the preparation of the sirup and the extraction of the oil 
from the seeds, the extraction of tannin has been recommended. 
The production of tannin extract is practicable only in the case of 
raisin seeds, since wine residues arc probably largely depleted of their 
tannin content. The tannin, being soluble in water, can be extracted 
in a practical way by boiling the meal in large digestion vats, the 
solution being transferred to vacuum pans for concentration to a 
moist extract. If a dry extract is preferred it can be obtained by 
simply allowing the moist extract to dry in the air. 

The large quantity of tannin extract which can be produced from 
raisin-seed meal and which is well adapted for the tanning of leather 
becomes the third important commercial product capable of being 
made from raisin seeds. 

The final residue, the meal, seemingly already exhausted of all its 
constituents of value, still possesses useful qualities. The stock- 
feeding value of the meal has been discussed and a comparison made 
with several standard stock foods. While possibly it is not equal to 
some of the standard press cakes and meals on the market, yet on 
account of its high protein content its usefulness as part, at least, of 
a stock-feeding ration can hardly be denied. 

276 

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